1. Field of the Invention
The present invention relates to a backlight on/off control apparatus for use in a liquid crystal display television (hereinafter "LCD TV") and more particularly, to an automatic backlight on/off control apparatus for automatically turning a backlight on/off according to existing or non-existing of a composite video signal.
2. Description of the Prior Art
Various types of backlight on/off control apparatuses having a backlight which is turned on according to the pulse signals of a pulse generating member are well known in the art. One of such conventional backlight of/off control apparatuses for an LCD TV is illustrated in FIG. 1. As shown in FIG. 1, since a transistor TR.sub.1 is turned on or off according to pulse signals of a pulse generating member 1, the voltage of a backlight voltage terminal Vcc is induced in the second winding of a transformer T, which causes a first capacitor C1 to be charged. The charged voltage of the capacitor C1 is applied to a backlight 2 through a second capacitor C.sub.2 to turn on the backlight 2. However, such conventional backlight on/off circuit includes the backlight 2 turned on according to the pulse signals of the pulse generating member 1 regardless of existing or non-existing of a video signal. Therefore, such conventional backlight on/off circuit has a drawback so that unnecessary power consumption increases.